Fusible link



May 26,- 1925.

W. K. HODGMN FUSIBLE LINK Filed Feb. l1. 1922 was /f Patented May 26, 1925.

UNITED STATES PATENT OFFICE.

WILLS K. HDGMAN, OF TAUNTON, hiiASSACHUS-ETTS; EMMA. HODGIVIAN EXECU- TRIX OF SAID WLLIS K. HODGMAN, DECEASED.

FUSIBLE LINK.

Application filed February 11,1922. Serial No. 535,797.

7'0 @U ifi/mm it may concern.: Y

Be it known that l, Tintas K. Honor/MN,

a citizen of the 1United States, residing at '.iaunton, in the county of llristol and State 5 of lilassachusetts, have invented new and useful improvements in Fusible Links, of

which the following is a specification.

My invention relates to improvements in fusible links used in automatic sprinklers for extinguishing lires, or in other devices wherein it is desirable to hold certain parts of the mechanism to which they are applied in assembled condition until a predetermined degree of temperature eXists in the vicinity of the apparatus and melts the solder uniting the parts of the links.

rihe objects of my invention are to provide a fusible link of superior efficiency as to both its holding and releasing functions.

l attain these objects, in a fusible link of the three piece type embodying the principle of the invention, by embodying two opposed plates ha ving` ceuntersunk appertures to connect with the n'ieehanisin to which they are applied and also having shoal transverse channels, substantially rectangular in cross section, which provide a chamber between the plates which is occupied by a fulcrumblock located substantially half and half in ao each of the plates, thus making a fusible link wherein the bearing surfaces of the apertures, the fulcrum-block and channels, which take the tension normally set up in the link, may be formed so as not only to provide a certain and positive tilting tend eucy to the fnlcrum-block but also to provide means whereby the major part of the tension is taken by the fulcrum-block and not by the solder uniting the parts of the 40 link.

In order that the principle of the invention may be readily understood, I have disclosed a single type or embodiment thereof in the accompanying drawing, in which- Figure l is a side elevation of my link;

and Fig. 2, is a vertical sectionon line 22,

Fig. l.

Similar numerals refer to similar parts throughout the several views.

My fusible link. as shown in the drawing, is of the three piece type and consists of the duplicate plates 3 and 4, the fulcrum-block and a fusible solder which melts at a predetermined degree of heat. The solder is applied between the opposed surfaces of the parts of the link in the usual manner but is not shown in the drawing.

Each of the plates is provided, near its outer end, with an aperture (l to receive one of the parts (not shown) to be held in asA sen'ibled condition.

rlhe inside face of each plate, near its inner end, is provided with a transverse channel 7, rectangular in section, and with sides perpendicular to the face of the plate.

The 'Fulcrum-block 5 `is slightly less in width than the channels 7 7, thus being free to tilt and pry the plates il and 4 apart when the solder melts, and its edges are curved outwardly or convexed as plainly shown in the drawing. The thickness of the fulcrum-block is twice the depth of each channel so it is normally located half and half in the channels. The object of the convex edges of the fulcrum-block 5 is to provide it with a certain and positive holding tendency caused by the bearing parts of said edges with the co-operating sides of the channels 7 7 being` thus definitely located in the plane of the inside faces of the plates 3 and 4.

Having described the holding properties peculiar to my fusible link I will new proceed to describe its peculiar releasing properties. Referring to Fig. 2, atten tion is directed to the fact that the apertures 6 G are countersunk from the .inside faces of the plates 3 and 4. The ob `iect of the countersinking of the apertures 6 G is to provide the plates 3 and 4 with a certain and positive separating tendency caused by the bearing surfaces of the apertures, with the co-operating surfaces of the parts held in assembled condition, being thus delinitely located on opposite sides of the plane of the inside faces of the plates 3 and 4.

The direction and plane of tension, when the fusible link is in normal condition, are indicated by the arrows above and below Fig. 2.

lt will now be understood that when the fusible link is in normal condition the major part of the tension will be taken by the fulcruin-block 5, because it is substantially in the plane of tension, leaving only the slight separating tendency caused by the countersunk apertures G 6 to be held by the fusible solder; and when the solder 1nelts the fulcrun'i-block Will tilt and pry the plates 3 and 4l completely apart.

I claim: Y

A fusible link comprising a pair of similar relatively thin l'la't plates'each having an aperture near one end and a 'transverse channel of rectangular cross section between the aperture and the opposite end, the said aperture being countersunk at its edge adjacent the end of the plate in which it is located and at the face of the plate in which the channel is located and a 'luleruni block having a thickness equal Ito the combined depths of said channels, 'having its longitudinal edges convex and having its Width slightly less than the Width of said channels Whereby when the link is assembled with the plates reversed endwise and with the channels facing each other and with the fulcruin block in the channels and the parts lunited by 'fusible sol-der, the majo-r part of the tension imparted to the link at the apertures will be taken by the fulcruin block and upon the melting of the solder a positive separating tendency is secured by the countersunk edges of the apertures presenting bearing edges deiinitely located on opposite sides of the plane of the adjacent faces of the plates. In witness whereof I aiiix my signature.

VILLIS K. HODGMAN. 

